Alternatively, we can express the NearPoint using the magnification M :

If we use for example a 1/2.5″ 5 Aptina Megapixel greyscale Sensor mit 2.2 pixel pitch, we can use the pixel diagonal as CoC for crisp images, say
A 5 Mega lens with f=7.2mm focal length and F-stop F2.4, focused to an object distance of 100mm then has a far point of
und einen Nahpunkt von
and thus

If instead we use a 5 Megapixel greyscale Sony Sensor with 3.45 pixel pitch, we can choose as CoC the diagonal of the pixel for crisp images, say
A 5 Mega lens with f=7.2mm focal length and F-stop F2.4, focussed to 100mm then results inmm
and a nearpoint of
thus we get

If we use a color sensor instead we can use for crisp images. For the two sensors above we then get:

To increase the DOF we can increase the Pixel Size, but we either lose resolution, or (at the same pixel count) the magnification changes)

Netwon’s Rings are a phenomenon of wave optics and occur if there is a small path difference of coherent light.
They occur for example for large spheres on a glass plate with a very small gap between sphere and plate.

Some light is reflected from the glass sphere’s surface and some is reflected from the glass plate’s surface.
Because the light is coherent, we get constructive and destructive interference.

For the gap being 1/4 Lambda, the path in the gap and back is lambda/2, which results in destructive interference. Same for path lengths in the gap of 3/2 lambda, 5/2, etc. Say, for gaps that are odd multiples of lambda 1/4.
For even multiples of lambda/4, say lambda/2 , 3/2 Lambda etc, we get constructive interference.

Say, we simply can count the bright rings. For 666nm red light for example, three rings are 1000nm = 1 micrometer, which is the length of the air gap.

Newton’s rings are used in lens production, together with interferometers to find how close the current shape is from the wanted shape.

Thus surface accuracies are given in “(Newton’s) Rings”. The less rings, the better the shape got to be (and the more expensive the lens will be). Also a diametre should be given, for example five rings in 18mm diameter.

Be an object point 20mm left of the first Focal point of a lens of 30mm focal length.
Then it’s image is to the right of the second Focal point (“-” 20 because the left of the focal point).

Be an object point 10mm left of the first Focal point of a lens of 30mm focal length.
Then it’s image is to the right of the second focal point (“-” 10 because the left of the focal point).

The advantage of Newton’s equation is that you can determine the focal point and distances from these focal points of lenses relatively easy, while principal points can be relatively difficult to determine.

A third inch lens with f = 6mm lens and a half-inch lens of f = 8mm have the same field of view!

Normal lenses help to define “wide angle lens” and “telephoto lenses”:
Lenses with a focal length less than that of a normal lens is called wide angle lens.
Lenses with a focal length greater than that of a normal lens are called telephoto lens.

However, an f = 8mm lens on a 1/3 sensor is a “(slight”) “tele lens and on a 1” sensor, a wide angle lens.